Platen-shifting mechanism.



T. E. BUSCHMANN. PLATEN SHIF'HNG MECHANISM.

' APPLICATION FILED JUNE 25, I913. 1,150,498.

Patented Aug. 17,1915.

2 sHsns-snsn 1.

T. E. BUSCHMANN. PLATEN SHIFTING MECHANISM. APPLICATION FILED JUNE 25.I913.

Patented Aug. 17, 1915.

EST 2.

2 SHEETS-SH THEODOR EUGEN BUSCHMANN, 0F CNITZ, GERMANY, ASSIGNOB, 'JM'.)THE E OF WANDERER WERKE VORM. W 5.; NEAR CHEMNITZ, GER-MANY.

-=OFER & JAENICKE, ABM-GEES 015' SGHON'AU,

PLATEN-STING MEG:

Specification of Letters Patent.

Application filed June 25, 1913. Serial No. 775,791.

To all whom it may concern Be it known that LTHEODOR EUGEN Boson- MANN,a subject of the Emperor of Ger-' many, residing at Chemnitz, Germany,have invented certain new and useful Improvements in Platen-ShiftingMechanism, of which the following is a specification.

This invention has for itsobject to provide an improved mechanism forshifting the platen in typewriters into the upper case position. As iswell known, in the ma orlty of such mechanisms the platen is raised forthe purpose of writing capitals or upper case characters. Now since insuch cases the platen is not fixed in position, it must be held in itsnormal position preferably by means of a catch or locking device, whilemeans must also be provided for limiting the extent of its risingmovement when being shifted.

Means have already been proposed for holding a platen in its lower caseposition and limiting its upward movement into its upper caseposition,but such known means have comprised a locking member situated outside ofthe shifting mechanism.

Now according to the present invention the members of the platenshifting mechanism are so constructed that they effect of themselves thedesired movement of the platen into its end positions. For this purpose,controlling members are interposed in the shifting mechanism, and aremounted on the shifting platen carrier (more particularly on theshifting frame) and they are arranged to-cooperate with each other insuch a manner that one of these members will always be in its holdingposition when the other member is in released position. To this endthere are preferably employed two toggle levers which engage theshifting frame and are moved by the shift key through the medium of bellcrank levers, in such a manner that one toggle lever will be extendedwhen the other toggle lever is bent.

It is to be understood that also other members may be interposed in theshifting mechanism to assist the operation. It is also to be noted thatone advantage of the improved mechanism is that the platen is movedalmost noiselessly into its several end positions.

Une form of this invention comprising the use of toggle levers isillustrated by Way of example in the accompanying drawings, in whichFigure 1 is a side elevation partly in section of a type-writer fittedwith the improved shifting mechanism. Fig. 2 is a corresponding partialfront elevation partly in section. Fig. 3 is a partial side elevationsimilar to Fig. 1, but showing the parts in a different workingposition. Figs. 4 and. 5 are views correspondin respectively to Figs. 1and 3, of a modi cation.

As shown, the platen 1 which is adjustably mounted and guided in thecarriage 2, rests by means of a sliding roller 4: on a shifting frame 5.This frame is adapted to slide at its upper end in guides 15 fixed tothe framing 3 of the typewriter, and it is supported at its lower end bya radius rod 14, which is pivoted to the typewriter framing 3.

The shifting frame 5 has a bent over portion or lug 6 carrying a pin onwhich the levers 11 and 12 are pivoted. The lever 11 is jointed to abell crank lever 10 which is pivoted to the typewriter frame, thearrangement being such that one arm of this bell crank lever 10 forms atoggle with the pivoted lever 11. The other arm of the bell crank lever10 is jointed to a rod 9 to the other end of which there is jointed anarm of a bell crank lever 13 likewise connected to the framing 3. Theother arm of this bell crank lever 13 forms a toggle with a pivotedlever 12. To the rod or link 9 there is jointed a radius rod 8 which isconnected to the shift key 7.

In the construction shown in Figs. 4- and 5, there is mounted on the pinin the lug 6 of the shift frame 5 a lever 11 as before, and also a lever17 which engages, by means of a hooked extension, the lever 11. In thisarrangement the lever 11 is connected to a lever 16 pivoted to thetypewriter frame 3 and it forms a toggle herewith. The lever 17 isjointed at its other end to a bell crank lever 13 which is connected bya radius rod or link 18 to the shift key lever 7.

The bell crank levers 10 and 13, and the lever 16 are fulcrumed on bolts20 secured in'the usual manner by nuts in the typewriters framing 3.These bolts are formed under their heads with eccentric collars orshoulders 21 (Fig. 2) for the purpose of enabling the toggle levers tobe adjusted relatively to each other.

The operation of the improved mechanism constructed as shown in Figs. 1,2 and 3, is as follows: In Fig. 1, the platen is shown in its lower caseposition, in which the toggle 10, 11 is extended, and the toggle 12, 13is bent. In this position the platenis held by the extended toggle 10,11 and protected from being moved by jolts or similar influences. If nowfor instance, the shift key 7 is held down for the purpose of writingcapitals, the rods 8 and 9 are raised.'the upper arm of the bell cranklever 10 is turned upward toward the right, and the toggle 10, 11 isbent. At the same time the toggle 12, 13 is extended so that the partsassume the position shown in Fig. 3. The extended position of the toggle12, 13 determines, that is, limits the movement of the platen. Thismovement may be altered, and a fine adjustment be efiected by means ofthe bolts 20 with the eccentric collars or shoulders 21. On releasingthe shift key, the load or weight of the rod 9 and link 8, as well asthe excess load due to the rear end of the shift key lever 7, areshifted from the end of the key lever to lever arm of the bell cranklever 13 that is pivoted to the lower end of link 8. If the shift-keylever 7 be provided with a retracting spring, as is customary, the pullof this spring is also transferred to the bell crank 13. This load,

whether the retracting spring be present or not. acts on the bell cranklever 13, being multiplied by the length of the bell crank arm connectedto the bar 9 to give this'lever a slight impulse and move it off itsdead center, whereupon an additional load due to the excess weight ofthe platen 1 (which is otherwise counterbalanced) forces the'shift frame5 downward, thereby reextending the toggle 10, 11 turning down the upperarm of the bell crank lever 10 and carrying the rod 9 down with it. Bythis means the bell crank lever 13 is turned down again, and the toggle12, 13 is bent again.

In the construction shown in Figs. 4 and 5, on holding down the shiftkey 7, the bell crank lever 13 is turned up toward the right through themedium of the link 18, and the toggle 13, 17 is extended, wherebythrough the medium of the hook 19 engaging behind the lever 11, thetoggle 11, 16 is bent. The return of the parts of the shifting mecha-Although the present invention has been described by way of example inits appli-' cation to a typewriter having a shift frame it is to beclearly understood that it is not limited to typewriters of this kind,and that the invention. is applicable to all shifting carriers orsupports for paper rollers.

I claim 1. In a typewriting machine, the combina: tion with the frame, avertically movable platen carrier and a shift key lever; of raising andlowering mechanism for the carrier including two toggles arrangedsubstantially in the plane of said lever and above one another, a pivoton said carrier at the adjacent ends of said toggles and common to bothof them, means to pivotally mount the opposite ends of the carrier onsaid frame, an arm extending from one member of one of the toggles thatis ivoted on said frame, to form a bell-crank ever therewith, and a linkconnecting said mechanism and key lever.

2. In a typewriting machine, the combination with a shiftable platencarrier and a platen shifting key lever; of two toggles connected tosaid carrier and operating alternately, means on one of said toggles toautomatically break the other of said toggles when straightened, andmeans to operatively connect one of the toggles to said key lever. I

3. In a typewriting machine, the combination with a shiftable platencarrier and a platen shifting key lever; of two toggles having theiradjacent ends pivotally connected to said carrier, one member of one ofthe toggles constituting a bell-crank lever and the other member thereofhaving an extension arranged to engage the other toggle, and means toconnect said bell-crank and key lever.

In testimony whereof I have affixed my signature.

THEODOK EUGEN BUSCHMANN. In the presence of- EMIL STEGER, WALTERKoran-3R.

